PerformanceCounterCategory.CounterExists Method (String, String)

Determines whether the specified counter is registered to the specified category on the local computer.

Namespace:  System.Diagnostics
Assembly:  System (in System.dll)

public static bool CounterExists(
	string counterName,
	string categoryName
)

Parameters

counterName
Type: System.String

The name of the performance counter to look for.

categoryName
Type: System.String

The name of the performance counter category, or performance object, with which the specified performance counter is associated.

Return Value

Type: System.Boolean
true, if the counter is registered to the specified category on the local computer; otherwise, false.

ExceptionCondition
ArgumentNullException

The categoryName is null.

-or-

The counterName is null.

ArgumentException

The categoryName is an empty string ("").

InvalidOperationException

The category name does not exist.

Win32Exception

A call to an underlying system API failed.

UnauthorizedAccessException

Code that is executing without administrative privileges attempted to read a performance counter.

NoteNote

To read performance counters in Windows Vista and later, Windows XP Professional x64 Edition, or Windows Server 2003, you must either be a member of the Performance Monitor Users group or have administrative privileges.

To avoid having to elevate your privileges to access performance counters in Windows Vista and later, add yourself to the Performance Monitor Users group.

In Windows Vista and later, User Account Control (UAC) determines the privileges of a user. If you are a member of the Built-in Administrators group, you are assigned two run-time access tokens: a standard user access token and an administrator access token. By default, you are in the standard user role. To execute the code that accesses performance counters, you must first elevate your privileges from standard user to administrator. You can do this when you start an application by right-clicking the application icon and indicating that you want to run as an administrator.

The following code example determines whether a PerformanceCounter exists. It gets a category name, counter name, and computer name from the command line, if they are given. It uses the static overloads of the CounterExists method to determine whether the specified PerformanceCounter name exists in the PerformanceCounterCategory. The overload is selected based on whether a computer name is provided.

public static void Main(string[] args)
{
    string categoryName = "";
    string counterName = "";
    string machineName = "";
    bool objectExists = false;

    // Copy the supplied arguments into the local variables. 
    try
    {
        categoryName = args[0];
        counterName = args[1];
        machineName = args[2]=="."? "": args[2];
    }
    catch(Exception ex)
    {
        // Ignore the exception from non-supplied arguments.
    }

    try
    {
        // Check whether the specified counter exists. 
        // Use the static forms of the CounterExists method. 
        if (machineName.Length==0)
        {
            objectExists = PerformanceCounterCategory.CounterExists(counterName, categoryName);
        }
        else
        {
            objectExists = PerformanceCounterCategory.CounterExists(counterName, categoryName, machineName);
        }

    }
    catch(Exception ex)
    {
        Console.WriteLine("Unable to check for the existence of " +
            "counter \"{0}\" in category \"{1}\" on " + 
            (machineName.Length>0? "computer \"{2}\".": "this computer.") + "\n" + 
            ex.Message, counterName, categoryName, machineName);
        return;
    }

    // Tell the user whether the counter exists.
    Console.WriteLine("Counter \"{0}\" "+ (objectExists? "exists": "does not exist") + 
        " in category \"{1}\" on " + (machineName.Length>0? "computer \"{2}\".": "this computer."), 
        counterName, categoryName, machineName);
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

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